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• avcodec : add a native SMPTE VC-2 HQ encoder

  10 février 2016, par Rostislav Pehlivanov

  avcodec : add a native SMPTE VC-2 HQ encoder
  This commit adds a new encoder capable of creating BBC/SMPTE Dirac/VC-2 HQ
  
  profile files.
  Dirac is a wavelet based codec created by the BBC a little more than 10
  
  years ago. Since then, wavelets have mostly gone out of style as they
  
  did not provide adequate encoding gains at lower bitrates. Dirac was a
  
  fully featured video codec equipped with perceptual masking, support for
  
  most popular pixel formats, interlacing, overlapped-block motion
  
  compensation, and other features. It found new life after being stripped
  
  of various features and standardized as the VC-2 codec by the SMPTE with
  
  an extra profile, the HQ profile that this encoder supports, added.
  The HQ profile was based off of the Low-Delay profile previously
  
  existing in Dirac. The profile forbids DC prediction and arithmetic
  
  coding to focus on high performance and low delay at higher bitrates.
  
  The standard bitrates for this profile vary but generally 1:4
  
  compression is expected ( 525 Mbps vs the 2200 Mbps for uncompressed
  
  1080p50). The codec only supports I-frames, hence the high bitrates.
  The structure of this encoder is simple : do a DWT transform on the
  
  entire image, split it into multiple slices (specified by the user) and
  
  encode them in parallel. All of the slices are of the same size, making
  
  rate control and threading very trivial. Although only in C, this encoder
  
  is capable of 30 frames per second on an 4 core 8 threads Ivy Bridge.
  
  A lookup table is used to encode most of the coefficients.
  No code was used from the GSoC encoder from 2007 except for the 2
  
  transform functions in diracenc_transforms.c. All other code was written
  
  from scratch.
  This encoder outperforms any other encoders in quality, usability and in
  
  features. Other existing implementations do not support 4 level
  
  transforms or 64x64 blocks (slices), which greatly increase compression.
  As previously said, the codec is meant for broadcasting, hence support
  
  for non-broadcasting image widths, heights, bit depths, aspect ratios,
  
  etc. are limited by the "level". Although this codec supports a few
  
  chroma subsamplings (420, 422, 444), signalling those is generally
  
  outside the specifications of the level used (3) and the reference
  
  decoder will outright refuse to read any image with such a flag
  
  signalled (it only supports 1920x1080 yuv422p10). However, most
  
  implementations will happily read files with alternate dimensions,
  
  framerates and formats signalled.
  Therefore, in order to encode files other than 1080p50 yuv422p10le, you
  
  need to provide an "-strict -2" argument to the command line. The FFmpeg
  
  decoder will happily read any files made with non-standard parameters,
  
  dimensions and subsamplings, and so will other implementations. IMO this
  
  should be "-strict -1", but I’ll leave that up for discussion.
  There are still plenty of stuff to implement, for instance 5 more
  
  wavelet transforms are still in the specs and supported by the decoder.
  The encoder can be lossless, given a high enough bitrate.
  Signed-off-by : Rostislav Pehlivanov <atomnuker@gmail.com>
  

  • [DH] libavcodec/Makefile
  • [DH] libavcodec/allcodecs.c
  • [DH] libavcodec/vc2enc.c
  • [DH] libavcodec/vc2enc_dwt.c
  • [DH] libavcodec/vc2enc_dwt.h
  • [DH] libavcodec/version.h

• We are hiring engineers to build an awesome product and platform used by millions of people

  16 février 2016, par Piwik Core Team — Jobs

  Are you ready for a new challenge ? Or maybe you know someone who is looking for a change ? We have some exciting problems to solve and are looking for senior developers to work with us and our community on our open source Piwik Analytics platform. Piwik is used by more than one million websites all over the world. It is deployed on more than 300.000 servers and some users track more than 1 billion actions per month.

  What is it like to work on Piwik ?

  We develop this software using modern PHP, MySQL, Redis, AngularJS and more. We provide several kind of APIs and a plugin architecture to allow developers to extend and change Piwik to their needs. However, we would not be Piwik if we stopped at this point ! We want to turn Piwik into an even more awesome product and platform.
  You can imagine there is a lot to do and many challenges to face !

  While one part is to always make Piwik scale better and to improve UI and UX, we also want to provide simple APIs to make the life of developers as pleasant as possible. We aim to solve things the right way and our thousands of unit, integration, system, JavaScript and screenshot tests help us to innovate and to not be afraid of change. We like clean code and constant improvements.

  The Piwik team lives in New Zealand, Europe (Poland, Germany) and in the U.S. We do the vast majority of our collaboration online. Our values include being open, transparent and sharing knowledge. For this we use tools like GitHub and Slack to communicate and Quake servers to take our minds off complex challenges. We are a small, flexible team, so when you come aboard, you will play an integral part in engineering and have a big impact on the product loved by so many people. You’ll help to create a welcoming environment for new contributors and set an example with your development practices and communications skills.

  Apply now, or spread the word !

  If you have strong skills in PHP send us an email with your CV and tell us a little about yourself and your experience in engineering complex applications.

  Apply for a job here http://piwik.org/jobs/ and if you’re maybe not the right candidate, contribute to the project by sharing this blog post and by sending it to your friends !

• FFMPEG : concat demuxer errors during execution

  1er novembre 2015, par lgaravaglia

  I’m trying to use the FFMPEG concat demuxer to create a "loop" of a single video.

  I first tried running this command :

  ffmpeg -f concat -i behzad.txt -c:v copy output_concat.avi

  My input text file is as follows :

  file 'G:\Masters_Thesis_Files\Honda_Database\Database1\Training\videos\behzad\behzad.avi'
  
  file 'G:\Masters_Thesis_Files\Honda_Database\Database1\Training\videos\behzad\behzad.avi'

  The input file is in raw format.

  After running the command I get the following output to the console and the video generated is just the first frame of my input video file.

  ffmpeg version N-74286-ge5774f2 Copyright (c) 2000-2015 the FFmpeg developers
  
    built with gcc 4.9.3 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
  
  isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
  
  le-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --
  
  enable-libdcadec --enable-libfreetype --enable-libgme --enable-libgsm --enable-l
  
  ibilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enab
  
  le-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --en
  
  able-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --ena
  
  ble-libtwolame --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc
  
   --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enabl
  
  e-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-lzma --ena
  
  ble-decklink --enable-zlib
  
    libavutil      54. 30.100 / 54. 30.100
  
    libavcodec     56. 57.100 / 56. 57.100
  
    libavformat    56. 40.101 / 56. 40.101
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 32.100 /  5. 32.100
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.101 /  1.  2.101
  
    libpostproc    53.  3.100 / 53.  3.100
  
  Input #0, concat, from 'behzad.txt':
  
    Duration: N/A, start: 0.000001, bitrate: 110806 kb/s
  
      Stream #0:0: Video: rawvideo, bgr24, 640x480, 110806 kb/s, 14.99 fps, 14.99
  
  tbr, 14.99 tbn, 14.99 tbc
  
  File 'output_concat.avi' already exists. Overwrite ? [y/N] y
  
  Output #0, avi, to 'output_concat.avi':
  
    Metadata:
  
      ISFT            : Lavf56.40.101
  
      Stream #0:0: Video: rawvideo, bgr24, 640x480, q=2-31, 110806 kb/s, 14.99 fps
  
  , 14.99 tbr, 14.99 tbn, 14.99 tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
  Press [q] to stop, [?] for help
  
  [avi @ 0000000004723360] Non-monotonous DTS in output stream 0:0; previous: 1186
  
  24821151886176, current: 118624821151886176; changing to 118624821151886177. Thi
  
  s may result in incorrect timestamps in the output file.
  
  [avi @ 0000000004723360] Too large number of skipped frames 118624821151886176 >
  
   60000
  
  av_interleaved_write_frame(): Invalid argument
  
  [avi @ 0000000004723360] Too large number of skipped frames 118624821151886176 >
  
   60000
  
  frame=    2 fps=0.0 q=-1.0 Lsize=     906kB time=-00:00:00.00 bitrate=N/A
  
  video:1800kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing
  
  overhead: unknown
  
  Conversion failed!

  I also tried to run the command with the codec set to h264, rather than just copying the codec. When I ran this command the output to the console still had the DTS errors, however, my output video contained the entire input video rather than just the first frame. It did not repeat the video like I expect.

  I should also specify, I’m running these commands in Windows using the latest version of Zeranoe FFMPEG.

  I’m still relatively inexperienced with FFMPEG, is there some part of the process that I’m doing wrong ?